Reading Plywood and OSB Grade Stamps (back of panel)Special thanks to Georgia Pacific for input to this page.
The span rating indicates the maximum inches between supports that the panel
may be applied. If there are two numbers, the first refers to roof applications, the
second to floor applications.
The exposure durability classification defines whether the panel should be used for
interior or exterior applications:
- Exterior panels have a fully waterproof bond and are designed
for applications subject to permanent exposure to the weather or moisture.
- Exposure 1 panels are designed for protected construction and industrial applications
and can be exposed to the elements for a short time, but not permanently.
- Exposure 2 panels are intended for protected construction and industrial applications
where the potential for conditions of high humidity and water leakage exist.
- Interior panels are manufactured with an interior grade glue and are intended for
interior applications only.
The thickness of the panel is also included on the stamp. Plywood is sized 1/32" under its called size.
Hence, 1/2" plywood measures 15/32".